Choosing The Correct Antifreeze

First of all the word Antifreeze is very
misleading in today's cars. Every article I have
read, Antifreeze is mentioned as a rust inhibitor
and lubricant, no one worries about the temperature
issues.

Have you ever seen the inside of an aluminum water
pump that was not adequately protected by the
corrosion inhibitors in the coolant? Or a radiator
or heater core that failed from the inside out
because of internal corrosion? These kinds of parts
failures are all too common. Yet they can be easily
prevented by using the “right” coolant and changing
the coolant before trouble starts to heat up.

All types of antifreeze contain corrosion-inhibiting
chemicals to protect bare metal surfaces from
electrolytic attack. Though automakers disagree on
which chemical additives work best in their
vehicles, essentially any kind of antifreeze will
work in any vehicle. But how well will it protect
the cooling system?

Always refer to the repair manual before topping off
your vehicle's coolant.

What makes choosing the right coolant so confusing
today is that the automakers themselves can’t agree
on what type of coolant chemistry is best for their
vehicles. Some vehicle manufacturers prefer one type
of corrosion inhibitors in their coolants, while
other vehicle manufacturers may insist on a
different type.

The fact is, all types of antifreeze contain
additives to protect the cooling system against
corrosion. So you wouldn’t think it would make any
difference which one you actually decided to use.
But some corrosion inhibitors are not compatible
with others, and if the chemistries differ too much,
it can reduce the coolant’s ability to prevent
corrosion as the coolant ages.

Adding a conventional green antifreeze to a cooling
system that contains an orange or yellow long-life
coolant will reduce the life of the coolant to that
of ordinary antifreeze (which for most vehicles is
typically two to three years or 30,000 miles). Most
long-life coolants, by comparison, are formulated to
go five years or 150,000 miles.

To distinguish one type of coolant from another,
vehicle manufacturers add colored dye to their
coolants. Unfortunately, the colors they use are not
necessarily standardized and do not always conform
to the same chemical specifications. Because of
this, two different coolants may use the same color
dye, or two similar coolants may use different
colored dyes. Most standard formula antifreeze is
dyed green, but there are also some standard formula
coolants that are yellow. Long-life coolants are
typically orange or yellow, but some may also be
red, pink, blue, purple or even green. Go figure.
Consequently, the idea of matching colors when
choosing a coolant doesn’t always guarantee success.

The Standard Green

Standard
green formula antifreeze is the type that most North
American vehicles used until the introduction of
extended-life coolants back in the mid-1990s. This
type of coolant contains fast-acting silicate and
phosphate corrosion inhibitors that protect cast
iron engines, bi-metal (cast iron/aluminum) engines,
and copper/brass and aluminum radiators. The
corrosion-fighting chemicals are fast-acting, but
wear out after two to three years or 36,000 miles of
average use, so green coolant needs to be changed
periodically to minimize the risk of corrosion
damage.

While this type of antifreeze is primarily for older
vehicles (pre-1996), it can also be used in
virtually any vehicle application (domestic, Asian
or European) regardless of year — provided all of
the old coolant is completely flushed and replaced
with new.

Extended Life OAT Formula

Antifreeze
that is dyed orange, typically contains
“Organic Acid Technology” (OAT) corrosion inhibitors
such as sebacate, 2-ethylhexanoic acid (2-EHA) and
other organic acids, but no silicates or phosphates.
The most familiar OAT-based product is Dex-Cool,
which General Motors has used since 1996. Orange
formula coolant is also used in the Mercury Cougar,
and 2003 and up Saabs. Similar formulas include a
pink-colored coolant in late-model Audi and
Volkswagen vehicles and a dark green coolant in
Hondas.

The corrosion inhibitors in OAT coolants are slower
acting than standard green formula coolant, but last
much longer. The service life for this type of
coolant is five years or 150,000 miles — which seems
like a long time, but it is not a lifetime coolant.
Eventually the corrosion inhibitors wear out and the
coolant needs to be changed.

Extended
Life Hybrid Coolants

Silicated Hybrid Organic Acid Technology (HOAT)
antifreezes, which are sometimes referred to as
“G-05” formula coolants, contain organic acids in
combination with one or more inorganic inhibitors.
The most common inhibitor is silicate. The addition
of silicates increases corrosion protection for
aluminum engines, radiators and heater cores, and
helps protect the water pump against erosion wear.
Silicated hybrid OAT coolants are specified for 2001
and up DaimlerChrysler vehicles, 2002 and up Ford
trucks and SUVs, 2003 and up Ford passenger cars,
and 1985 and up Mercedes, BMWs, Volvos and Mini
Coopers.

“Phosphated HOAT” coolants are used in Asian
vehicles (Toyota, Honda, Nissan, Kia and Hyundai)
because Asian vehicle manufacturers prefer
phosphated organic acid coolants and do not like
silicated organic acid coolants. European vehicle
manufacturers, on the other hand, generally specify
silicated HOAT coolants and do not like phosphated
organic acid coolants. That’s why some antifreeze
suppliers offer different HOAT formulas for these
applications.

Universal Formulations

Universal
formula antifreezes are marketed as being suitable
for all passenger cars and light trucks, regardless
of year, make or model, or the type of coolant
that’s already in the cooling system. Some of these
claims have been challenged in court on the basis
that no single additive package can match the
conflicting requirements of different OEM coolants.
Even so, the makers of universal coolant say their
products can be used in any vehicle, whether it
matches the original coolant chemistry or not.

The universal coolants use OAT-based corrosion
inhibitors with proprietary organic acids to provide
broad spectrum protection. The coolant may be dyed
yellow or amber (yellow-orange).

The service life of most universal formula products
is typically five years or 150,000 miles — with one
exception. When used to top off a cooling system in
an older vehicle that contains standard green
formula coolant, the service life of the product is
reduced to that of the original coolant, which is
two to three years or 30,000 miles.

The main advantages of a universal coolant is that
it simplifies the selection process to a single
product, and it eliminates the need to carry three
different types of coolant (green, orange and yellow
hybrid) to cover the market.

Those who are opposed to universal coolants say one
product cannot match the conflicting coolant
requirements of all the different vehicle
manufacturers, and that it is safer to offer three
different types of coolants that meet these
specifications. Consequently, many parts stores
carry not only the three basic types of coolant just
described (often in several different brands), but
also a universal coolant for customers who prefer
that type of product. When choosing a coolant,
therefore, refer to the vehicle owner’s manual for
the type recommended (or the label on the coolant
reservoir under the hood) to find a coolant that
meets the OEM requirements. Or, you may want to
choose an acceptable universal coolant.